1. Field of the Technology
The present invention relates to measurement techniques in the communication field, and more particularly, to a method and system for measuring network performance.
2. Description of the Related Art
With the rapid development of Internet technologies and swift growth of network services, a great demand for network resources has been emerging, and meanwhile the network is becoming more and more complicated. The increasing network subscribers and applications exert heavy burden on the network and cause overloading operations of network equipments, thus affecting the network performance. Therefore, the performance metrics of the network need to be extracted and analyzed to improve the network performance. As a result, the network performance measurement emerges as required. The main purpose of the network performance measurement is discovering network bottlenecks, optimizing network configurations, and further recognizing potential dangers in the network, so as to more efficiently perform the network performance management, provide verification and control of the network service quality, and quantize, compare, and verify the service quality index of the service provider.
The most commonly adopted method for measuring IP network performance can be classified into two categories, namely, active measurement and passive measurement. The active measurement includes employing a measurement tool to purposely and actively generate a measurement flow on a selected measurement point, then injecting the flow into a network, and analyzing the network performance by measuring the transmission condition of a data flow. The passive measurement includes employing a measurement device to monitor a network on a link or device (such as a router or switch) without generating unwanted flows.
The performance measurement can be classified into one-way network performance measurement and two-way network performance measurement in terms of direction. The one-way network performance measurement means measuring the network performance metrics in only one direction from a measurement point A to the other measurement point B. The two-way network performance measurement means measuring the network performance metrics from a measurement point A to the other measurement point B and then back to the measurement point A. For a P2P communication, the traveling path varies in the to-and-fro directions, or the quality of service (QoS) varies on the same path in the to-and-fro directions, so the one-way network performance is not simply obtained by dividing the two-way delay by two, and in the subsequent descriptions, the network performance measurement is one-way network performance measurement without particular emphasis.
Generally, a measurement system is constituted by a measurement controller and measurement points deployed in a network. The active measurement method substantially includes the following steps:
1. The measurement controller configures two measurement points A, B participating in the performance measurement;
2. The measurement point A constructs a probe packet attached with a serial number and time stamp information, and sends the probe packet to the measurement point B. That is to say, the source IP address of the probe packet is the address of the measurement point A, and the destination IP address thereof is the address of the measurement point B; and
3. If the measurement point B receives the probe packet, a delay of the packet can be obtained, according to the sending time stamp carried by the probe packet and the time stamp information on receiving the packet. If the measurement point B does not receive the probe packet, a packet loss situation can be determined according to the consecutive serial number, and a packet loss ratio is thus obtained. Further, other performance metrics such as variation and network unavailability can be deduced from the delay and the packet loss ratio.
For the current network generally adopting IPv4, in order to solve the problem of insufficient IP address resources, the deployment of network address translation/network address port translation (NAT/NAPT) is very common, as shown in FIG. 1. As for the active measurement, if the NAPT/NAT exists on an end-to-end path, the NAT/NAPT device shields the internal network and blocks the transparency of the internal network. During the research, the inventor discovers that though the measurement points located in the internal network and the external network can normally receive/transmit the probe packet and calculate the network performance metrics, the measurement point in the external network is unable to determine whether a probe packet comes from the internal network or the external network (as the NAT/NAPT device has already translated a private IP address into a public IP address), nor actively access the measurement point in the internal network.
In an IPv4/IPv6 hybrid networking environment, if a network address translation-protocol translation (NAT-PT) technique is adopted to communicate an IPv4 network with an IPv6 network, the mapping between IPv4 addresses and IPv6 addresses is performed on an NAT-PT device, and thus the problem occurring to the NAT/NAPT on the active network performance measurement still exists.